1. Field of the Invention
The present invention is directed to a process and a system to emulate a mainframe data channel for testing and diagnostics of mainframe peripheral devices. In particular, the present invention is directed to a device to emulate a mainframe channel which is self-contained and portable and permits testing and diagnostics of mainframe peripheral devices and permits remote control and configuration of the testing and diagnostics.
2. Prior Art
Mainframe channels are known, independent hardware and software components that coordinate input and output functions (I/O) between a mainframe central processing unit and a set of controllers or devices. Mainframe channels are used in computer systems, such as mainframes, that handle channel input/output operations independently of the computer system's central processing unit. A channel is an independent hardware and software component that coordinates all input and output instructions to a set of controllers or devices. Each channel may support one or more controllers and one or more devices. Channel programs are software that contain lists of commands to the channel device itself and to the various controllers and devices to which they are connected.
A mainframe has channels which allow peripheral equipment such as tape drives, direct access storage devices (DASD, or very large hard drives) and printers to be attached to the mainframe. Equipment directly attaching to a mainframe channel is commonly known as a control unit, or controller, through which one or more peripheral devices may be accessed.
The earliest generation of mainframe channels used a parallel (aka BUS and TAG) multiple copper coax cable architecture by which controllers could be attached in a daisy-chained manner. Parallel channels were slow, bulky and nowadays rarely encountered. The next generation utilized a serial fibre optic architecture called Enterprise Serial Connection (ESCON, aka Single Byte protocol or SB-1) which evolved into the Fibre Channel Connection (FICON, aka Single Byte protocol 2 or SB-2), each offering point-to-point connectivity.
In order that a single serial channel might connect to more than a single controller, equipment known as directors, which are enterprise-class switches, may be employed serving as a dynamic patch panel. A director also allows more than a single mainframe channel to be attached to it and, generally, any channel may reach any controller. Utilizing a director is known as switched point-to-point connectivity and conforms to a typical hub and spoke networking design.
Various people are interested in the operation of mainframe computers. These include mainframe designers, engineers needing to field test mainframes, and customers desiring to ensure correct function prior to committing to the addition of new equipment to their production environment. In each instance in the past, it was required that the facilities of a mainframe be available to them. This has sometimes been accomplished through the use of an additional test mainframe, which is typically complex and expensive to maintain.
The costs entailed by a mainframe computer are substantial, requiring numerous personnel and equipment. Hardware staff and vendors manage and connect the hardware, systems software personnel load and configure the software onto it, and operations staff monitor it, responding to important events requiring intervention. Further, mainframes may be configured to run one of a number of operating system types, not all of which offer a conducive environment for testing equipment.
A channel command word (CCW) is a command used to perform an I/O operation. CCWs are often chained to form channel programs.
Although there are existing standard channel programs, additional complexities arise in how custom channel programs are developed and executed on a host mainframe. Unless a user is satisfied with using pre-existing utilities such as a copy routine, the user must develop channel programs using Assembler language which is fairly arcane and exceedingly complex when compared to higher level languages. To make matters worse, these programs must be placed into authorized locations meaning that data security personnel must become involved at some point. The user must also be able to log onto the system, submit jobs into it, ensure they become started, then use some host mainframe facility to process the final results.
Finally, designing of new peripheral devices and new channel programs requires testing.
In addition to serving as a facility for testing existing devices, the invention affords the ability to aid with the design of new peripherals. Using it, an equipment manufacturer can quickly test various channel program sequences to aid in two areas: first, to ensure the device behaves as intended during its design and second, to develop and optimize the channel programs for introduction into host mainframe utilities to be created to operate the new equipment. Since the invention is devoted towards this type of function, it is far easier to use than a mainframe, allowing a developer to focus on the tasks he needs to accomplish rather than having to deal with the complexities of a mainframe's environment.
There remains a need to provide a mainframe channel emulator which can be operated independent of a mainframe computer for testing and diagnostics of mainframe peripheral devices.
There remains a need for a mainframe channel emulator which permits remote control and configuration of the testing and diagnostics.
There remains a need for a mainframe channel emulator which is self-contained and portable.
There also remains a need for a mainframe channel emulator which may be remotely controlled via a secure connection and a secure procedure.